In this paper, the functional nano-Fe3O4 composite fabrics with good magnetic properties were fabricated througha combined chemical co-precipitation and finishing method. The particle size and magnetic properties of Fe3O4 weremeasured using Malvern Laser Particle Size Analyzer and vibrating sample magnetometer (VSM), respectivily. Thestructure, magnetic flux and mechanical property of the composite fabric were characterized by Fourier infrared spectrometry(FT-IR), X-ray diffraction (XRD), Tesla meter and Instron electronic tensile machine. The particle-size of prepared Fe3O4 isnano-scale and has excellent magnetic properties. The nano-Fe3O4/nylon composite fabrics have good magnetism,mechanical property and water repellency. The maximum magnetic flux of nano-Fe3O4 composite fabric is 2.4 mT.